Generating ferro-spinetic polarizations in altermagnetic insulators

TL;DR

This paper introduces the concept of charge and spinetic polarizations in altermagnetic insulators, revealing their coupling, origin, and potential for spintronics, supported by theoretical analysis and first-principles calculations.

Contribution

It establishes the fundamental role of charge and spinetic polarizations in altermagnetic insulators and their coupling, supported by symmetry analysis and first-principles calculations.

Findings

Identification of charge and spinetic polarizations in altermagnetic insulators.

Coupling of the two polarizations and their emergence in orthogonal directions.

Presence of large, switchable spin accumulations in these materials.

Abstract

Altermagnets are a novel class of fully spin-compensated magnetic materials that nevertheless have spin-split electronic bands, offering novel perspectives for spintronics applications. Based on a rigorous analysis of altermagnetic many-body models and their symmetry we establish the important role of two fundamental types of polarizations in altermagnetic insulators: the charge and the spinetic one, where the latter corresponds to a macroscopic spin-displacement field. First principles calculations confirm and quantify their presence in real materials. The two polarizations are directly coupled and emerge in orthogonal directions when inversion symmetry is broken, either by the system developing a spontaneously ferroelectric polarization (in ferroelectric altermagnets), or by a charge displacement induced by an external electric field (for inversion invariant altermagnetic insulators). This presence of large and switchable spin accumulations constitute an attractive fundamental feature of altermagnetic insulators.